1. Field of the Invention
The present invention relates to a semiconductor manufacturing apparatus, as well as a diagnostic module for semiconductor wafer transfer equipment that constitutes a semiconductor manufacturing apparatus.
2. Description of the Related Art
Wafer displacement that occurs on the semiconductor wafer transfer equipment of the semiconductor manufacturing apparatus has become a major problem in the production of semiconductor wafers in recent years. To be specific, when a semiconductor wafer is placed at a position displaced from the specified position in the semiconductor wafer processing chamber, process problems such as non-uniform film occur. Other problems may also occur, such as a semiconductor wafer dropping inside the semiconductor wafer storage chamber, or hitting the chamber and consequently getting damaged, in the process of returning the semiconductor wafer to the semiconductor wafer storage chamber.
One cause of this wafer displacement is change in the shape of the semiconductor wafer transfer equipment. For example, some processes implemented in semiconductor wafer processing chambers apply heat to semiconductor wafers. In this case, the tip parts of the semiconductor wafer transfer equipment that hold a semiconductor wafer (this tip part is sometimes called an “end effector”) undergo heat expansion as they transfer heated semiconductor wafers. The coefficient of expansion varies depending on the material used to make the tip part of the semiconductor wafer transfer equipment. In the case of aluminum, for example, which is used for tip parts of semiconductor wafer transfer equipment, if the temperature of the semiconductor wafer is 400° C. and the temperature of the tip part is approx. 200° C., the tip part expands by approx. 1.5 mm.
Here, occurrence of heat expansion in the semiconductor wafer transfer equipment means that the tip part extends in the direction of transferring semiconductor wafers. As a result, the semiconductor wafer clamping mechanism described later on, which is attached to the semiconductor wafer transfer equipment, pushes the semiconductor wafer outward and consequently the semiconductor wafer becomes displaced toward the outer periphery from the specified position. FIGS. 2, 3 and 4 illustrate examples of a semiconductor wafer transfer equipment with a semiconductor wafer clamping mechanism. FIG. 3 shows an example of a semiconductor wafer clamping mechanism in a semiconductor wafer transfer equipment. FIG. 4 shows an example of a condition where a semiconductor wafer W is placed on a semiconductor wafer transfer equipment. This semiconductor wafer transfer equipment has an end effector 22 on a transfer arm 26 which in turn is installed rotatably on a base 27, and a wafer damper 21 is provided on a proximal end of the end effector 22. The damper 21 has arms on both sides of the end effector and a pad 25 which is used to push the substrate is provided on a distal end of each arm. The wafer W placed on the end effector 22 is pushed by the damper 21 in the direction toward the distal end of the end effector (=in the direction of the arrow), and the end is secured by pads 23 provided on the distal end of the end effector 22 (for your information, the proximal end of the wafer is secured by pads 24 provided on the proximal end of the end effector 22). As shown in FIG. 4, the semiconductor wafer is secured at the pads 23 at the tips (locations indicated by circles) by means of the clamping mechanism. If the end effector itself extends, however, the distance to each pad 23 becomes longer, as shown in FIG. 9, and consequently the semiconductor wafer is pushed toward the outer periphery, or in the direction of the arrow, and becomes displaced. Take note that FIG. 9 is exaggerated for the purpose of illustration.
Another cause of wafer displacement is wear and tear of mechanisms inside the semiconductor wafer transfer equipment. As a considerable number of semiconductor wafers are transferred, the motor and other mechanical parts change over time and consequently the stopping position of the end effector of the semiconductor wafer transfer equipment displaces from the specified position.